我试图检查数据库中是否已经存在daet，但它显示warning:mysqli_num_rows()期望参数1为mysqli_result。
<?php
$sql_d = "SELECT * FROM programarii WHERE date_time='$dateTime";
$res_u = mysqli_query($conn, $sql_d);
if (mysqli_num_rows($res_u) > 0) {
$dateTimeErr = "Sorry date not available";
}
?>
您的查询中缺少一个‘。 尝试:
$sql_d = "SELECT * FROM programarii WHERE date_time='$dateTime'";
重要提示:我强烈建议您使用PDO来构建查询，因为您现在容易受到SQL注入的攻击。
编辑:
请尝试如下所示:
$dsn = "mysql:host=localhost;dbname=mydb";
$user = "root";
$passwd = "andrea";
$pdo = new PDO($dsn, $user, $passwd);
$dateTime = '2020-05-23 23:00';
$stm = $pdo->prepare("SELECT * FROM programarii WHERE date_time = ?");
$stm->bindValue(1, $dateTime);
$stm->execute();
$rows = $stm->fetchAll(PDO::FETCH_ASSOC);
if(count($rows)>0)
{
print('date not available');
}
